Browsing by Author "Steinmann, C. M."

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    Experimental conditions for vacuum ultraviolet laser spectroscopy
    (Academy of Science for South Africa, 2005) Du Plessis, A.; Steinmann, C. M.; Rohwer, E. G.
    An efficient wavelength-tunable vacuum ultraviolet (VUV) laser source has been developed at our institute in recent years. This laser source works on the principle of sum-frequency mixing of dye laser pulses in a magnesium vapour medium, which is prepared in a crossed heat pipe system. The laser source is coupled to a pulsed supersonic expansion and is in use for spectroscopic measurements. In this paper, we present a complete characterization of the experimental setup. The source yielded 25-ns-long pulses of VUV radiation with peak power of approximately 1 mW. The wavelength is currently tunable over the range 142.7-146.7 nm with a spectral bandwidth of 0.25 ± 0.05 cm -1. Suggested refinements of the experimental technique include an increase in the repetition rate of the measurements and shorter gas pulses.
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    High-resolution vacuum ultraviolet laser spectroscopy of molecules in a free supersonic jet : in search of rare CO isotopomers and CO-Ar van der Waals molecules
    (Academy of Science for South Africa, 2005) Steinmann, C. M.; Du Plessis, A.; Rohwer, E. G.
    Tunable vacuum ultraviolet radiation (in the range 142.7-146.7 nm) from a novel laser source was used to probe the electronic excitation spectrum of cold carbon monoxide molecules in a supersonic noble gas jet. Rotationally resolved spectra of 12C16O,13C16O, as well as the rare but astronomically important 12C18O and 12C17O isotopomers, were recorded. Evidence was obtained for the formation of CO-containing van der Waals complexes in the jet.